It's like saying that Italians are Romans or Greeks are Spartans (although most Greeks I met identify themselves with old Athens)
People (and the world) evolve and stop doing things their ancestors did. In this case they won't stop being Nordics, but they stopped being Vikings for the reasons you expose.
The rest of Europe are glad you are
What entire population did Spain kill? Don't come with the crap that Spain killed the whole Aztecs and Incas. You only need to go to Madrid or Barcelona tube (underground) and see that it's false because it's full of their descendants. And even if it was (it wasn't), it wasn't Spain, it was Castille.
Portugal? Same without the Tube. Go to Brazil, go deep into the Amazon
(not the online store) rainforest, and find there are still tribes there.
English slave trade? Yes, it wasn't that bad for the time standards. You can't judge people then by today's standards. At least the "Oh, so Christian countries" then (during the Middle Ages) only traded with pagan slaves (officially at least).
Fact only for readers interested in History:
The word "slave" in most western languages (slave, Sklave, esclavo, esclau, esclave, esklabo, escravo, slaaf, etc.) have a common origin: The word for Slavic peoples, the easiest to get pagan peoples during 8th-11th Centuries. They were so common that their name displaced the Latin word "Servus".
I will give you a piece of free advice: Read. Read History books. Read anything and compare it with other sources to know if what you read is true. Get your facts right before posting on the internet and ridiculing yourself. I know it's hard to read so many words. I know books don't have a CTRL key. But try it. It's for your own good.